Although gas chromatograph mass spectrometer (GCMS) is a robust and reliable technique to monitor and determine constituents of a gas sample, the significant size and cost has appealed for inexpensive and smaller detection methods. Nowadays, sensor manufacturers are producing instruments that have more advanced detection capabilities and cover a wider range of advanced applications by using micromachined technology. While continuing to use mature technologies, vehicle manufacturers for example are increasing the sophistication of the electronic systems used in their products. Many manufacturers clamor for chemical sensors to provide real-time analysis of, for example, exhaust fumes and determine the concentration of hydrocarbons in fuel vapors recovery systems.
In general, gas sensors operate by a variety of fundamentally different mechanisms. Ionization sensors work by fingerprinting the ionization characteristics of distinct gases, but they are limited by their huge bulky architecture.